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arXiv quant-ph/9904095quant-ph
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基于相干态重构方法的量子自旋离散相空间计算

A Discrete Phase-Space Calculus for Quantum Spins based on a Reconstruction Method using Coherent States

Stefan Weigert

摘要:

通过相干态可以重建自旋s的混合量子态或纯量子态:它的密度矩阵由在空间中沿4s(s+1)个适当选择的方向测量s值的概率固定。因此,在反演实验数据之后,统计算子完全由期望值参数化。在此基础上,发展了一种量子自旋的符号演算,即“期望值表示”。它类似于SU(2)的Moyal表示,但存在两个重要的差异。一方面,符号仅在相空间中的离散点集上取值。另一方面,在这种方法中没有遇到准概率-即具有负值的相空间分布。

英文摘要:

To reconstruct a mixed or pure quantum state of a spin s is possible through coherent states: its density matrix is fixed by the probabilities to measure the value s along 4s(s+1) appropriately chosen directions in space. Thus, after inverting the experimental data, the statistical operator is parametrized entirely by expectation values. On this basis, a symbolic calculus for quantum spins is developed, the `expectation-value representation.' It resembles the Moyal representation for SU(2) but two important differences exist. On the one hand, the symbols take values on a discrete set of points in phase space only. On the other hand, no quasi-probabilities - that is, phase-space distributions with negative values - are encountered in this approach.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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